1. Field of the Invention
The present invention relates to a seatbelt system for protecting the occupant by restraining him in an emergency of the vehicle, and more particularly to a seatbelt system wherein a lap webbing and a shoulder webbing can be wound up by a single take-up shaft doubly.
2. Description of the Prior Art
Heretofore, there have been widely used such seatbelt systems that two retractors for separately winding up a shoulder webbing to restrain the shoulder of the occupant and a lap webbing to restrain the lap of him are provided, so that the operations can be smoothly performed by the occupant when he puts the webbings on so as to be restrained and when he releases the restraint, and the motion of the occupant who wears the webbings can be made easy to ensure pleasant fitness.
As against the above, recently, there has been proposed the so-called double wind-up type retractor wherein a lap webbing and a shoulder webbing are doubly wound up by a single take-up shaft, whereby the same functional effect is achieved as the separate retractors are provided for the respective webbings. In this seatbelt system in which the double wind-up retractor is used, use of a single retractor suffices, so that an inexpensive seatbelt system can be provided without hampering the smooth movement of the webbings when the occupant puts on or releases them and pleasant fitness when he wears them, thereby obtaining high evaluation.
However, with this double wound-up type retractor, when only the internally wound webbing out of the doubly wound up webbings is wound out, the outernally wound webbing is wound out following the internally wound webbing and the externally wound webbing thus followingly wound out is not acted on by tension, and hence, may loosened to block the retractor casing. For this, the movement of the occupant may become larger by the value thus loosened in an emergency of the vehicle.